Re: /var/log/messages doesn't have crash info when kernel gets panic/oops/crash

Dharmosoth Seetharam
2009-06-13T13:22:58Z

> -----Original Message-----
> From: ebiederm@xmission.com
> Sent: Sat, 13 Jun 2009 05:51:25 -0700
> To: dseetharam@inbox.com
> Subject: Re: /var/log/messages doesn't have crash info when kernel gets
> panic/oops/crash
>
> Dharmosoth Seetharam <dseetharam@inbox.com> writes:
>
>>> -----Original Message-----
>>> From: ebiederm@xmission.com
>>> Sent: Sat, 13 Jun 2009 00:11:25 -0700
>>> To: dseetharam@inbox.com
>>> Subject: Re: /var/log/messages doesn't have crash info when kernel gets
>>> panic/oops/crash
>>>
>>> Dharmosoth Seetharam <dseetharam@inbox.com> writes:
>>>
>>>> Hi Neil,
>>>>
>>>> Thanks for your quick reply.
>>>>
>>>> What you have suggested is nice when we got/save crash dump (i.e
>>>> vmcore)
>>>> What if we failed to save/capture vmcore info or vmcore is corrupted
>>>> etc. then we dont get any information
>>>> regarding the panic/crash/oops at anywhere?
>>>
>> Hi Eric,
>>
>>> Basic questions.
>>> 1) Do you have panic on oops set?
>>> I think that setting more than anything else will be the
>>> difference in what shows up in /var/log/messages.
>>
>> Yes, in my case panic_on_oops was set with 1
>
> That is the reason thing don't show up in /var/log/messages
> because you panic before syslog has a chance to write the messages.

Thanks.
So, if panic_on_oops set with 0(default), we will get all the
needed info like stack traces, bug info etc. in /var/log/messages then reboots.

Or do we need to apply any specific patches to get info in /var/log/messages?

>
>>> 2) Have you tried a dry run and confirmed you can get a crash dump?
>>
>> No, I haven't tried this.
>
> It sounds like you have not been getting the coredumps when problems
> happen. Running a simple test run to Alt-sysrq-c to confirm
> that things are basically setup ok is a good idea.
>
Sorry, I misunderstood your question.
I have gave dry run and confirmed that the dumps are getting saved in particular dir and able to analyze.

I did in both the ways like
1 - echo c > /proc/sysrq-trigger
2 -Alt -sysrq -c

thanks,
Seetharam

>>> 3) Are you using kvm
>> kvm? kernel virtual memory?
>
> Kernel virtual machine. In particular.
> Hardware acceleration for virtual machines.
>
> Eric

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